Leishmania spp. genetic factors associated with cutaneous leishmaniasis antimony pentavalent drug resistance: a systematic review.

BACKGROUND: Leishmaniasis is a neglected zoonosis caused by parasites of Leishmania spp. The main drug used to treat cutaneous leishmaniasis (CL) is the antimoniate of meglumine. This drug, which has strong adverse and toxic effects, is usually administered intravenously, further complicating the difficult treatment. Factors such as Leishmania gene expression and genomic mutations appear to play a role in the development of drug resistance. OBJECTIVES: This systematic review summarises the results of the literature evaluating parasite genetic markers possibly associated with resistance to pentavalent antimony in CL. METHODS: This study followed PRISMA guidelines and included articles from PubMed, SciELO, and LILACS databases. Inclusion criteria were studies that (i) investigated mutations in the genome and/or changes in gene expression of Leishmania associated with treatment resistance; (ii) used antimony drugs in the therapy of CL; (iii) used naturally resistant strains isolated from patients. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess article quality and risk of bias. FINDINGS: A total of 23 articles were selected, of which 18 investigated gene expression and nine genomic mutations. Of these 23 articles, four examined gene expression and genomic mutations in the same samples. Regarding gene expression, genes from the ABC transporter protein family, AQP1, MRPA, TDR1 and TRYR were most frequently associated with drug resistance. In one of the articles in which mutations were investigated, a mutation was found in HSP70 (T579A) and in three articles mutations were found in AQP1 (A516C, G562A and G700A). A limitation of this review is that in most of the included studies, parasites were isolated from cultured lesion samples and drug resistance was assessed using in vitro drug susceptibility testing. These approaches may not be ideal for accurate genetic evaluation and detection of treatment failure. MAIN CONCLUSIONS: The development of further studies to evaluate the genetic resistance factors of Leishmania spp. is necessary to elucidate the mechanisms of the parasite and improve patient treatment and infection control.

Use of topical rSm29 in combination with intravenous meglumine antimoniate in the treatment of cutaneous leishmaniasis: A randomized controlled trial.

BACKGROUND: Cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis is associated with an inflammatory response. Granzyme (GzmB) and IL-1ß play a key role in the pathology. Meglumine antimoniate (MA) is the first-choice drug for the treatment of CL, but therapy failure is observed in up to 50% of the cases. The protein, rSm29 of Schistosoma mansoni, down-modulates pro-inflammatory cytokine production. We evaluate if the combination of topical rSm29 plus MA increases the cure rate of CL. METHODS: In this randomized clinical trial, 91 CL patients were allocated in 3 groups. All cases received MA (20 mg/kg/weight) for 20 days. Group 1 used topical rSm29 (10 µg), group 2 a placebo topically applied, and group 3 received only MA. RESULTS: The cure rate on day 90 was 71% in subjects treated with rSm29 plus MA, and 43% in patients who received MA plus placebo or MA alone (P < 0.05). There was a decrease in GzmB and an increase in IFN-γ (P < 0.05) in supernatants of skin biopsies of the lesions obtained on D7 of therapy (P < 0.05) in patients who received rSm29. CONCLUSION: rSm29 associated with MA reduces GzmB levels, is more effective than MA alone, and decreases CL healing time. CLINICAL TRIALS REGISTRATION: ClinicalTrial.gov under NCT06000514.

Microemulsions strongly promoted the activity of α-bisabolol against different Leishmania species and its skin permeation.

This study aimed to develop microemulsions (MEs) containing α-bisabolol for the topical treatment of cutaneous leishmaniasis (CL). Initially, pseudoternary phase diagrams were developed using α-bisabolol as the oil phase, Eumulgin® CO 40 as the surfactant, Polymol® HE as the co-surfactant, and distilled water as the aqueous phase. Two transparent liquid systems (TLS) containing 5% of α-bisabolol were selected and characterized (F5E25 and F5EP25). Next, skin permeation and retention assays were performed using Franz cells. The interaction of the formulation with the stratum corneum (SC) was evaluated using the FTIR technique. The cytotoxicity was evaluated in murine peritoneal macrophages. Finally, the antileishmanial activity of microemulsions was determined in promastigotes and amastigotes of L. amazonensis (strain MHOM/BR/77/LTB 0016). As a result, the selected formulations showed isotropy, nanometric size (below 25 nm), Newtonian behavior and pH ranging from 6.5 to 6.9. The MEs achieved a 2.5-fold increase in the flux and skin-permeated amount of α-bisabolol. ATR-FTIR results showed that microemulsions promoted fluidization and extraction of lipids and proteins of the stratum corneum, increasing the diffusion coefficient and partition coefficient of the drug in the skin. Additionally, F5E25 and F5EP25 showed higher activity against promastigotes (IC50 13.27 and 18.29, respectively) compared to unencapsulated α-bisabolol (IC50 53.8). Furthermore, F5E25 and F5EP25 also showed antileishmanial activity against intracellular amastigotes of L. amazonensis, with IC50 50 times lower than free α-bisabolol and high selectivity index (up to 15). Therefore, the systems obtained are favorable to topical administration, with significant antileishmanial activity against L. amazonensis promastigotes and amastigotes, being a promising system for future in vivo trials.

Antileishmanial activity of a dillapiole derivative obtained from Piper aduncum L. (Piperaceae).

Cutaneous leishmaniasis (CL) is considered a public health problem. Current treatments have disadvantages because they are invasive and have serious side effects, and thus there is a need for research into new, more effective pharmacological alternatives. Plants are promising sources of bioactive substances, and new analogues can be obtained through chemical reactions. The present study aimed to evaluate the antileishmanial effects of the analog dillapiole n-butyl ether (DBE) extracted from Piper aduncum leaves. The cytotoxic potential of DBE was evaluated at concentrations of 15.62 to 500 µM in peritoneal macrophages for 48 h, and in RAW 264.7 macrophages for 72 h using a dose-response method. The antileishmanial activity in L. amazonensis promastigotes used concentrations of 0.2 to 4.5 µM for 24, 48 and 72 h and the quantification of the cellular infection rate used a concentration of 4.5 µM of DBE against the amastigote forms internalized in macrophages for 24 h and 48 h. Nitric oxide was quantified from macrophages previously treated with DBE for 24 h and 48 h. The dosage of reactive oxygen species used a concentration of 4.5 µM of DBE incubated together with dichlorofluorescein acetate for 1, 3, 6, and 24 h. For the molecular modeling of DBE, the Leishmania protein, available in the "Protein Data Bank" database, was used. The studied molecule was not toxic to cells and presented a CC50 of 413 µM in peritoneal macrophages and 373.5 µM in RAW 264.7. The analogue inhibited promastigote forms of L. amazonensis with an IC50 of 1.6 µM for 72 h. DBE presented an infection rate of 17% and 12%, dillapiole of 24% and 14% and Pentacarinat® of 10% and 9% over 48 h. DBE demonstrated a binding energy of -7.8 for the U53 enzyme. It is concluded that the analogue showed promising antileishmanial activity for future in vivo tests.

Case Report: Cutaneous Leishmaniasis: A Case Series with Intralesional Treatment in Northeast Brazil.

In 2022, the Pan American Health Organization recommended the intralesional application (IL) of pentavalent antimonials in adult patients with localized cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis. Other guidelines differ from that recommendation, considering that infections caused by a Leishmania species that can be associated with increased risk for mucosal leishmaniasis, in particular L. (V.) braziliensis, should not be eligible for intralesional treatment. This was a prospective interventional study carried out with eight patients diagnosed with CL residing in northeast Brazil during the period from 2019 to 2022. To our knowledge, this is the first prospective study on the subject conducted in the northeast region, which has the second-highest number of cases in the country. In our sample, clinical cure was achieved with the use of intralesional treatment in all cases, and there were no serious adverse events or mucosal involvement during the 1-year follow-up period. We emphasize the importance of using the right criteria for choosing this therapeutic modality and highlight the advantages of intralesional treatment due to the lower risk of adverse events and cost reduction to health services.

Severe Inflammatory and Disseminated Cutaneous Leishmaniasis in a Pregnant Woman: A Case Report from Portoviejo, Ecuador.

BACKGROUND Leishmaniasis is a zoonosis with worldwide prevalence that causes dermal lesions and can be serious in humans. This report presents a case of cutaneous leishmaniasis (CL) that was apparently associated with a zoonotic transmission in a peri-urban area of the city of Portoviejo, Ecuador, close to mountainous and forested sites. CASE REPORT For 37 years, we have studied transmission of leishmaniasis in Ecuador, and have seen a wide variety of clinical presentations of the disease caused by different strains of the parasite Leishmania in patients, including pregnant women, without marked difference among them. CL without complications causes painless lesions of different clinical aspect. The present study reports a case of a 25-year-old woman presenting with severely inflamed, disseminated, and painful lesions of CL. The patient was not given antimonial treatment; however, local cryotherapy was given, together with topical anti-inflammatory and antibiotic ointment. All the lesions were observed to heal, and no amastigotes were found in smear stains after clinical healing. Since there was no reactivation after 1.5 years of follow-up, conventional antileishmanial treatment with meglumine antimoniate was not given to the patient. CONCLUSIONS This report shows the importance of a properly done epidemiological and clinical presumtive diagnosis, followed by parasitological confirmation, and the benefit of using an alternative treatment for vulnerable patients, such as this pregnant woman, for whom the therapy with pentavalent antimonials is not indicated. All observed lesions healed and no amastigotes were found in the smears after clinical healing.

Photodynamic therapy offers a novel approach to managing miltefosine-resistant cutaneous leishmaniasis.

Cutaneous leishmaniasis (CL) is a neglected disease caused by Leishmania parasites. The oral drug miltefosine is effective, but there is a growing problem of drug resistance, which has led to increasing treatment failure rates and relapse of infections. Photodynamic therapy (PDT) combines a light source and a photoactive drug to promote cell death by oxidative stress. Although PDT is effective against several pathogens, its use against drug-resistant Leishmania parasites remains unexplored. Herein, we investigated the potential of organic light-emitting diodes (OLEDs) as wearable light sources, which would enable at-home use or ambulatory treatment of CL. We also assessed its impact on combating miltefosine resistance in Leishmania amazonensis-induced CL in mice. The in vitro activity of OLEDs combined with 1,9-dimethyl-methylene blue (DMMB) (OLED-PDT) was evaluated against wild-type and miltefosine-resistant L. amazonensis strains in promastigote (EC50 = 0.034 µM for both strains) and amastigote forms (EC50 = 0.052 µM and 0.077 µM, respectively). Cytotoxicity in macrophages and fibroblasts was also evaluated. In vivo, we investigated the potential of OLED-PDT in combination with miltefosine using different protocols. Our results demonstrate that OLED-PDT is effective in killing both strains of L. amazonensis by increasing reactive oxygen species and stimulating nitric oxide production. Moreover, OLED-PDT showed great antileishmanial activity in vivo, allowing the reduction of miltefosine dose by half in infected mice using a light dose of 7.8 J/cm2 and 15 µM DMMB concentration. In conclusion, OLED-PDT emerges as a new avenue for at-home care and allows a combination therapy to overcome drug resistance in cutaneous leishmaniasis.

Natural resistance to meglumine antimoniate is associated with treatment failure in cutaneous leishmaniasis caused by Leishmania (Viannia) panamensis.

The multifactorial basis of therapeutic response can obscure the relation between antimicrobial drug susceptibility and clinical outcome. To discern the relationship between parasite susceptibility to meglumine antimoniate (SbV) and therapeutic outcome of cutaneous leishmaniasis, risk factors for treatment failure were considered in evaluating this relationship in ninety-one cutaneous leishmaniasis patients and corresponding clinical strains of Leishmania (Viannia) panamensis. Parasite susceptibility to 32 µg SbV/mL (plasma Cmax) was evaluated in primary human macrophages, PBMCs, and U937 macrophages. Early parasitological response to treatment was determined in lesions of a subgroup of patients, and pathogenicity of Sb-resistant and sensitive clinical strains was compared in BALB/c mice. Parasite survival in cell models and patient lesions was determined by qRT-PCR of Leishmania 7SLRNA transcript. Parasite loads in BALB/c mice were quantified by limiting dilution analysis. The disparate Sb-susceptibility of parasite subpopulations distinguished by isoenzyme profiles (zymodemes) was manifest in all cell models. Notably, Sb-resistance defined by parasite survival, was most effectively discerned in U937 macrophages compared with primary human host cells, significantly higher among strains from patients who failed treatment than cured and, significantly associated with treatment failure. Each unit increase in transformed survival rate corresponded to a 10.6-fold rise in the odds of treatment failure. Furthermore, treatment failure was significantly associated with naturally Sb-resistant zymodeme 2.3 strains, which also produced larger lesions and parasite burdens in BALB/c mice than Sb-sensitive zymodeme 2.2 strains. The confounding effect of host risk factors for treatment failure in discerning this association was evidenced in comparing strains from patients with and without the defined risk factors for treatment failure. These results establish the association of natural resistance to meglumine antimoniate with treatment failure, the importance of host risk factors in evaluating drug susceptibility and treatment outcome, and the clinical and epidemiological relevance of natural Sb-resistance in L. (V.) panamensis subpopulations.

4-Quinolinylhydrazone analogues kill Leishmania (Leishmania) amazonensis by inducing apoptosis and mitochondria-dependent pathway cell death.

Despite efforts, available alternatives for the treatment of leishmaniasis are still scarce. In this work we tested a class of 15 quinolinylhydrazone analogues and presented data that support the use of the most active compound in cutaneous leishmaniasis caused by Leishmania amazonensis. In general, the compounds showed activity at low concentrations for both parasitic forms (5.33-37.04 µM to promastigotes, and 14.31-61.98 µM to amastigotes). In addition, the best compound (MHZ15) is highly selective for the parasite. Biochemical studies indicate that the treatment of promastigotes with MHZ15 leads the loss of mitochondrial potential and increase in ROS levels as the primary effects, which triggers accumulation of lipid droplets, loss of plasma membrane integrity and apoptosis hallmarks, including DNA fragmentation and phosphatidylserine exposure. These effects were similar in the intracellular form of the parasite. However, in this parasitic form there is no change in plasma membrane integrity in the observed treatment time, which can be attributed to metabolic differences and the resilience of the amastigote. Also, ultrastructural changes such as vacuolization suggesting autophagy were observed. The in vivo effectiveness of MHZ15 in the experimental model of cutaneous leishmaniasis was carried out in mice of the BALB/c strain infected with L. amazonensis. The treatment by intralesional route showed that MHZ15 acted with great efficiency with significantly reduction in the parasite load in the injured paws and draining lymph nodes, without clinical signs of distress or compromise of animal welfare. In vivo toxicity was also evaluated and null alterations in the levels of hepatic enzymes aspartate aminotransferase, and alanine aminotransferase was observed. The data presented herein demonstrates that MHZ15 exhibits a range of favorable characteristics conducive to the development of an antileishmanial agent.

Amphotericin B resistance in Leishmania amazonensis: In vitro and in vivo characterization of a Brazilian clinical isolate.

In Brazil, Leishmania amazonensis is the etiological agent of cutaneous and diffuse cutaneous leishmaniasis. The state of Maranhão in the Northeast of Brazil is prevalent for these clinical forms of the disease and also has high rates of HIV infection. Here, we characterized the drug susceptibility of a L. amazonensis clinical isolate from a 46-year-old man with diffuse cutaneous leishmaniasis coinfected with HIV from this endemic area. This patient underwent several therapeutic regimens with meglumine antimoniate, liposomal amphotericin B, and pentamidine, without success. In vitro susceptibility assays against promastigotes and intracellular amastigotes demonstrated that this isolate had low susceptibility to amphotericin B, when compared with the reference strain of this species that is considered susceptible to antileishmanial drugs. Additionally, we investigated whether the low in vitro susceptibility would affect the in vivo response to amphotericin B treatment. The drug was effective in reducing the lesion size and parasite burden in mice infected with the reference strain, whereas those infected with the clinical isolate and a resistant line (generated experimentally by stepwise selection) were refractory to amphotericin B treatment. To evaluate whether the isolate was intrinsically resistant to amphotericin B in animals, infected mice were treated with other drugs that had not been used in the treatment of the patient (miltefosine, paromomycin, and a combination of both). Our findings demonstrated that all drug schemes were able to reduce lesion size and parasite burden in animals infected with the clinical isolate, confirming the amphotericin B-resistance phenotype. These findings indicate that the treatment failure observed in the patient may be associated with amphotericin B resistance, and demonstrate the potential emergence of amphotericin B-resistant L. amazonensis isolates in an area of Brazil endemic for cutaneous leishmaniasis.

Complex cutaneous leishmaniasis in a pediatric patient.

Cutaneous leishmaniasis (CL), a parasitic infection caused by Leishmania protozoa and transmitted by sandfly bites, can be classified into Old World and New World subtypes. We report a case of a 2-year-old female who developed complex CL after travel to Panama. Ultimately, successful treatment required two rounds of liposomal amphotericin B. We report this case for its challenging clinical course and management.

Development of a topical treatment for tegumentary leishmaniasis using 8-hydroxyquinoline.

In the context of neglected diseases, tegumentary leishmaniasis (TL) presents an emerging and re-emerging character in the national territory and in the world. The treatment of TL has limitations, such as intravenous administration route, high toxicity, and high treatment costs. Thus, several researchers work on new therapeutic strategies to improve the effectiveness of the treatment of leishmaniasis. In this light, the present study used a topical formulation, containing 8-hydroquinoline (8-HQN), for the treatment of Balb/c mice infected with L. amazonensis. After the treatment, the mean diameter of the lesion was measured, as well as the parasite load in organs and immunological parameters associated with the treatment. The results showed that the animals treated with 8-HQN 5%, when compared to controls, showed a reduction in the mean diameter of the lesion and in the parasite load. The animals treated with the ointment showed a type 1 cellular immune response profile associated with the production of cytokines such as INF-γ and TNF-α. In addition, the treatment did not demonstrate toxicity to mice. Therefore, the topical formulation containing 8-HQN 5% is a promising candidate in the topical treatment and could be considered, in the future, as an alternative for the treatment of TL.

Local amphotericin B therapy for Cutaneous Leishmaniasis: A systematic review.

BACKGROUND: Cutaneous leishmaniasis (CL) is characterized by potentially disfiguring skin ulcers carrying significant social stigma. To mitigate systemic drug exposure and reduce the toxicity from available treatments, studies addressing new local therapeutic strategies using available medications are coming up. This review systematically compiles preclinical and clinical data on the efficacy of amphotericin B (AmB) administered locally for cutaneous leishmaniasis. METHODOLOGY: Structured searches were conducted in major databases. Clinical studies reporting cure rates and preclinical studies presenting any efficacy outcome were included. Exclusion criteria comprised nonoriginal studies, in vitro investigations, studies with fewer than 10 treated patients, and those evaluating AmB in combination with other antileishmanial drug components. PRINCIPAL FINDINGS: A total of 21 studies were identified, encompassing 16 preclinical and five clinical studies. Preclinical assessments generally involved the topical use of commercial AmB formulations, often in conjunction with carriers or controlled release systems. However, the variation in the treatment schedules hindered direct comparisons. In clinical studies, topical AmB achieved a pooled cure rate of 45.6% [CI: 27.5-64.8%; I2 = 79.7; p = 0.002), while intralesional (IL) administration resulted in a 69.8% cure rate [CI: 52.3-82.9%; I2 = 63.9; p = 0.06). In the direct comparison available, no significant difference was noted between AmB-IL and meglumine antimoniate-IL administration (OR:1.7; CI:0.34-9.15, I2 = 79.1; p = 0.00), however a very low certainty of evidence was verified. CONCLUSIONS: Different AmB formulations and administration routes have been explored in preclinical and clinical studies. Developing therapeutic technologies is evident. Current findings might be interpreted as a favorable proof of concept for the local AmB administration which makes this intervention eligible to be explored in future well-designed studies towards less toxic treatments for leishmaniasis.

Casiopeina III-ia: A Copper Compound with Potential Use for Treatment of Infections Caused by Leishmania mexicana.

INTRODUCTION: Casiopeina III-ia (CasIII-ia) is a mixed chelate copper (II) compound capable of interacting with free radicals generated in the respiratory chain through redox reactions, producing toxic reactive oxygen species (ROS) that compromise the viability of cancer cells, bacteria and protozoa. Due to its remarkable effect on protozoa, this study evaluated the effect of CasIII-ia on Leishmania mexicana amastigotes and its potential use as a treatment for cutaneous leishmaniasis in the murine model. METHODS: We analyzed the leishmanicidal effect of CasIII-ia on L. mexicana amastigotes and on their survival in bone marrow-derived macrophages. Furthermore, we evaluated the production of ROS in treated parasites and the efficacy of CasIII-ia in the treatment of mice infected with L. mexicana. RESULTS: Our results show that CasIII-ia reduces parasite viability in a dose-dependent manner that correlates with increased ROS production. A decrease in the size of footpad lesions and in parasite loads was observed in infected mice treated with the intraperitoneal administration of CasIII-ia. CONCLUSIONS: We propose CasIII-ia as a potential drug for the treatment of cutaneous leishmaniasis.

Nanoemulsions containing amphotericin b and paromomycin for the treatment of cutaneous leishmaniasis.

Cutaneous leishmaniasis (CL) is a vector-borne disease characterized by skin lesions that can evolve into high-magnitude ulcerated lesions. Thus, this study aimed to develop an innovative nanoemulsion (NE) with clove oil, Poloxamer® 407, and multiple drugs, such as amphotericin B (AmB) and paromomycin (PM), for use in the topical treatment of CL. METHODS: Droplet size, morphology, drug content, stability, in vitro release profile, in vitro cytotoxicity on RAW 264.7 macrophages, and antileishmanial activity using axenic amastigotes of Leishmania amazonensis were assessed for NEs. RESULTS: After optimizing the formulation parameters, such as the concentration of clove oil and drugs, using an experimental design, it was possible to obtain a NE with an average droplet size of 40 nm and a polydispersion index of 0.3, and these parameters were maintained throughout the 365 days. Furthermore, the NE showed stability of AmB and PM content for 180 days under refrigeration (4 °C), presented a pH compatible with the skin, and released modified AmB and PM. NE showed the same toxicity as free AmB and higher toxicity than free PM against RAW 264.7 macrophages. The same activity as free AmB, and higher activity than free PM against amastigotes L. amazonensis. CONCLUSION: It is possible to develop a NE for the treatment of CL; however, complementary studies regarding the antileishmanial activity of NE should be carried out.

Treatment using vanillin-derived synthetic molecules incorporated into polymeric micelles is effective against infection caused by Leishmania amazonensis species.

Treatment against leishmaniasis presents problems, mainly due to the toxicity of the drugs, high cost, and the emergence of resistant strains. A previous study showed that two vanillin-derived synthetic molecules, 3s [4-(2-hydroxy-3-(4-octyl-1H-1,2,3-triazol-1-yl)propoxy)-3-methoxybenzaldehyde] and 3t [4-(3-(4-decyl-1H-1,2,3-triazol-1-yl)-2-hydroxypropoxy)-3-methoxybenzaldehyde], presented antileishmanial activity against Leishmania infantum, L. amazonensis, and L. braziliensis species. In the present work, 3s and 3t were evaluated to treat L. amazonensis-infected mice. Molecules were used pure or incorporated into Poloxamer 407-based micelles. In addition, amphotericin B (AmpB) and its liposomal formulation, Ambisome®, were used as control. Animals received the treatment and, one and 30 days after, they were euthanized to evaluate immunological, parasitological, and biochemical parameters. Results showed that the micellar compositions (3s/Mic and 3t/Mic) induced significant reductions in the lesion mean diameter and parasite load in the infected tissue and distinct organs, as well as a specific and significant antileishmanial Th1-type immune response, which was based on significantly higher levels of IFN-γ, IL-12, nitrite, and IgG2a isotype antibodies. Drug controls showed also antileishmanial action; although 3s/Mic and 3t/Mic have presented better and more significant parasitological and immunological data, which were based on significantly higher IFN-γ production and lower parasite burden in treated animals. In addition, significantly lower levels of urea, creatinine, alanine transaminase, and aspartate transaminase were found in mice treated with 3s/Mic and 3t/Mic, when compared to the others. In conclusion, results suggest that 3s/Mic and 3t/Mic could be considered as therapeutic candidates to treat against L. amazonensis infection.

N6-methyltubercidin gives sterile cure in a cutaneous Leishmania amazonensis mouse model.

Leishmania is a trypanosomatid parasite that causes skin lesions in its cutaneous form. Current therapies rely on old and expensive drugs, against which the parasites have acquired considerable resistance. Trypanosomatids are unable to synthesize purines relying on salvaging from the host, and nucleoside analogues have emerged as attractive antiparasitic drug candidates. 4-Methyl-7-ß-D-ribofuranosyl-7H-pyrrolo[2,3-d]pyrimidine (CL5564), an analogue of tubercidin in which the amine has been replaced by a methyl group, demonstrates activity against Trypanosoma cruzi and Leishmania infantum. Herein, we investigated its in vitro and in vivo activity against L. amazonensis. CL5564 was 6.5-fold (P = 0.0002) more potent than milteforan™ (ML) against intracellular forms in peritoneal mouse macrophages, and highly selective, while combination with ML gave an additive effect. These results stimulated us to study the activity of CL5564 in mouse model of cutaneous Leishmania infection. BALB/c female and male mice infected by L. amazonensis treated with CL5564 (10 mg kg−1, intralesional route for five days) presented a >93% reduction of paw lesion size likely ML given orally at 40 mg kg−1, while the combination (10 + 40 mg kg−1 of CL5564 and ML, respectively) caused >96% reduction. The qPCR confirmed the suppression of parasite load, but only the combination approach reached 66% of parasitological cure. These results support additional studies with nucleoside derivatives.

Topical application of ozonated sunflower oil accelerates the healing of lesions of cutaneous leishmaniasis in mice under meglumine antimoniate treatment.

Besides being scarce, the drugs available for treating cutaneous leishmaniasis have many adverse effects. Ozone is an option to enhance the standard treatment due to the wound-healing activity reported in the literature. In this study, we evaluated the efficiency of ozonated sunflower oil as an adjuvant in treating cutaneous lesions caused by Leishmania amazonensis. BALB/c mice were infected with L. amazonensis, and after the lesions appeared, they were treated in four different schedules using the drug treatment with meglumine antimoniate (Glucantime®), with or without ozonated oil. After thirty days of treatment, the lesions' thickness and their parasitic burden, blood leukocytes, production of NO and cytokines from peritoneal macrophages and lymph node cells were analyzed. The group treated with ozonated oil plus meglumine antimoniate showed the best performance, improving the lesion significantly. The parasitic burden showed that ozonated oil enhanced the leishmanicidal activity of the treatment, eliminating the parasites in the lesion. Besides, a decrease in the TNF levels from peritoneal macrophages and blood leukocytes demonstrated an immunomodulatory action of ozone in the ozonated oil-treated animals compared to the untreated group. Thus, ozonated sunflower oil therapy has been shown as an adjuvant in treating Leishmania lesions since this treatment enhanced the leishmanicidal and wound healing effects of meglumine antimoniate.

Antiprotozoal potential of Vismia species (Hypericaceae), medicinal plants used to fight cutaneous leishmaniasis.

ETHNOPHARMACOLOGICAL RELEVANCE: Species of Vismia (Hypericaceae), known in Brazil as "lacre", are commonly used in traditional Amazonian medicine for the treatment of skin lesions, including those caused by Leishmania infection. AIM OF THE STUDY: Hexane extracts from the leaves of Vismia cayennensis, V. gracilis, V. sandwithii and V. guianensis, as well as from the fruits of the latter, in addition to the anthraquinones vismiaquinone, physcion and chrysophanol isolated from these species were explored for their anti-promastigote and anti-amastigote activity on Leishmania amazonensis. MATERIALS AND METHODS: Extracts were prepared by static maceration with n-hexane. The compounds, isolated by chromatographic techniques, were identified by spectroscopic methods (1H and 13C NMR). Promastigotes of L.amazonensis were incubated with hexane extracts (1-50 µg/mL) or anthraquinones (1-50 µM) and the parasite survival analyzed. The action of compounds on reactive oxygen species (ROS) production, mitochondrial membrane potential, and membrane integrity of promastigotes were evaluated by flow cytometer, and the cytotoxicity on mammalian cells using MTT assay. Furthermore, the activity of compounds against amastigotes and nitric oxide production were also investigated. RESULTS: Vismiaquinone and physcion were obtained from the leaves of V. guianensis. Physcion, as well as chrysophanol, were isolated from V. sandwithii. Vismia cayennensis and V. gracilis also showed vismiaquinone, compound detected in lower quantity in the fruits of V. guianensis. All extracts were active against the parasite, corroborating the popular use. The greatest activity against promastigotes was achieved with V. guianensis extract (IC50 4.3 µg/mL), precisely the most used Vismia species for treating cutaneous leishmaniasis. Vismiaquinone and physcion exhibited relevant activity with IC50 12.6 and 2.6 µM, respectively. Moreover, all extracts and anthraquinones tested induced ROS production, mitochondrial dysfunction, membrane disruption and were able to kill intracellular amastigote forms, being worthy of further in vivo studies as potential antileishmanial drugs. CONCLUSIONS: The overall data achieved in the current investigation scientifically validate the traditional use of Vismia species, mainly V. guianensis, as an anti-Leishmania agent. Furthermore, the promising results presented here indicate species of Vismia as potentially useful resources of Brazilian flora for the discovery of therapeutic solutions for neglected diseases.